PX: February 2009 Archives

The structure of XPD was solved using data collected at the SIBYLS beamline and published in Cell this past summer. Recently this outstanding work was featured in the ALS Science Highlights.

"XPD helicase is an enzyme that unwinds the DNA double helix; it is one component of an essential repair mechanism that maintains the integrity of DNA. XPD is unique, however, in that pinpoint mutations of this single protein are responsible for three different human diseases: in xeroderma pigmentosum (XP), extreme sensitivity to sunlight promotes cancer; Cockayne syndrome (CS) involves stunted growth and premature aging; trichothiodystrophy (TTD), characterized by brittle hair and scaly skin, is another form of greatly accelerated aging. At the ALS, researchers from Berkeley Lab and The Scripps Research Institute recently solved the structure of XPD. The structure gives novel insight into the processes of aging and cancer by revealing how discrete flaws--as seemingly insignificant as a change in either of two adjacent amino acid residues--can lead to diseases with completely different physical manifestations."